US3641281A - Magnetic transducer having a conductive metal powder gap spacer - Google Patents
Magnetic transducer having a conductive metal powder gap spacer Download PDFInfo
- Publication number
- US3641281A US3641281A US870293A US3641281DA US3641281A US 3641281 A US3641281 A US 3641281A US 870293 A US870293 A US 870293A US 3641281D A US3641281D A US 3641281DA US 3641281 A US3641281 A US 3641281A
- Authority
- US
- United States
- Prior art keywords
- metal powder
- gap
- head
- magnetic transducer
- gap spacer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000000843 powder Substances 0.000 title claims abstract description 11
- 229910052751 metal Inorganic materials 0.000 title claims abstract description 7
- 239000002184 metal Substances 0.000 title claims abstract description 7
- 125000006850 spacer group Chemical group 0.000 title abstract description 4
- 230000004907 flux Effects 0.000 claims abstract description 5
- 239000004020 conductor Substances 0.000 claims description 3
- 239000000696 magnetic material Substances 0.000 claims description 2
- 239000000463 material Substances 0.000 description 14
- 239000011521 glass Substances 0.000 description 12
- 239000010410 layer Substances 0.000 description 9
- 238000000034 method Methods 0.000 description 9
- 229910000859 α-Fe Inorganic materials 0.000 description 7
- 239000000919 ceramic Substances 0.000 description 4
- 239000011162 core material Substances 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- 239000004372 Polyvinyl alcohol Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000004033 plastic Substances 0.000 description 3
- 229920003023 plastic Polymers 0.000 description 3
- -1 polyethylene Polymers 0.000 description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 description 3
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000000020 Nitrocellulose Substances 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 229920002472 Starch Polymers 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- 239000012790 adhesive layer Substances 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229920001220 nitrocellulos Polymers 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 229920000915 polyvinyl chloride Polymers 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 2
- 239000008107 starch Substances 0.000 description 2
- 235000019698 starch Nutrition 0.000 description 2
- 229920003051 synthetic elastomer Polymers 0.000 description 2
- 239000005061 synthetic rubber Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000002196 Pyroceram Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 241000656145 Thyrsites atun Species 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229910001922 gold oxide Inorganic materials 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000005355 lead glass Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910000595 mu-metal Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920001490 poly(butyl methacrylate) polymer Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 239000005020 polyethylene terephthalate Substances 0.000 description 1
- 229920000139 polyethylene terephthalate Polymers 0.000 description 1
- 229920002689 polyvinyl acetate Polymers 0.000 description 1
- 239000011118 polyvinyl acetate Substances 0.000 description 1
- 229940072033 potash Drugs 0.000 description 1
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Substances [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/127—Structure or manufacture of heads, e.g. inductive
- G11B5/187—Structure or manufacture of the surface of the head in physical contact with, or immediately adjacent to the recording medium; Pole pieces; Gap features
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/4902—Electromagnet, transformer or inductor
- Y10T29/49021—Magnetic recording reproducing transducer [e.g., tape head, core, etc.]
- Y10T29/49032—Fabricating head structure or component thereof
- Y10T29/49036—Fabricating head structure or component thereof including measuring or testing
- Y10T29/49039—Fabricating head structure or component thereof including measuring or testing with dual gap materials
Definitions
- FIG.2 l Claims, 3 Drawing Figures l 8 m 1 4 m 3 FIG! FIG.2
- the invention pertains to a transducer head for magnetic recording and reproducing apparatus and is particularly suitable for recording and reproducing very high frequency signals which occuramong others-in predetection recording of radar signals or recording and reproducing television programs on magnetizable medium.
- the capability of the magnetic head of reproducing very high frequencies or, as they appear on the magnetizable medium, very short wavelengths is primarily determined by the nonmagnetic transducer gap in the head and the core material.
- the transducer head in the reproducer head must be considerably less than the wavelength on the medium.
- a numerical example will illustrate the order of magnitudes. Let us assume that the recorded signal is 5 Mc./sec. and that the head-to-medium speed is 1,000 in./sec. Even at that high relative speed the recorded wavelength is 200 microinches long and it is desirable to keep the reproducer head gap to say 100 microinches.
- the object of the invention is to provide a magnetic head with a very short and controlled nonmagnetic transducer gap.
- a further object of the invention is to provide this gap by a method suitable for mass production.
- Another object of the invention is to provide the gap in such a manner which disposes with the spring or retainer or casting which is necessary when applying any of the previously known methods.
- FIG. 1 is the side view of a magnetic head.
- the first pole piece 1 and the second pole piece 2 each are carefully lapped along AA and BB and are wound with coils 33 and 44.
- the core material may be any high permeability material such as Mu-metal, ferrite etc.
- the transducer gap 11 is formed by a layer of glass which forms an inseparable bond with the core material. Whereas in the past attempts have been made to use glass as gap spacer material, technological difficulties prevented it from becoming a practical proposition.
- the gap is formed by means of a heavily loaded plastic foil which is called transfer tape.”
- This heavily loaded transferable tape can be prepared from glass, glazing or ceramic material to accurate thickness.
- the transferable tape is prepared by laminating a slurry containing a suitably low particle size powder onto a carrier film. The thickness and density of this laminated layer can be accurately controlled prior to its application. The layer of the heavily loaded tape can then be transferred from its carrier to the pole faces of the magnetic transducer head to be coated,
- a typical transferable tape thus, consists of:
- a thin, uniform carrier film of materials such as polyethylene, polyvinylchloride or Teflon;
- a binder such as nitrocellulose, polybutylmethacrylate or polyvinylalcohol and plasticizer.
- the ratio of these components can be varied according to the shape of the pole pieces from 98 percent solid powder and 2 percent plastic material to 36 percent solid powder and 64 percent plastic material.
- adhesive layer such as starch, synthetic rubber or polyvinylalcohol.
- the preparation of the transferable tape is per se known and not claimed as an invention.
- the carrier film 5 which can be e.g., polyethylene, polyvinylchloride or Teflon carries the heavily loaded layer 6 which is glass, glazing or ceramic powder uniformly distributed in a film-forming material such as nitrocellulose, polyacrylates or polyvinylacetate.
- a further layer 7 is an adhesive such as starch, synthetic rubber or polyvinylalcohol.
- the transducer gap is prepared by bringing the ferrite head in contact with the transfer tape under small pressure. On removing the ferrite head from the transfer tape, the heavily loaded layer will adhere to the area of the ferrite head which was in contact with the tape.
- the transducer gap can now be completed by pressing according to the desired gap thickness a clean or a similarly treated part 9 against part 8 and holding them in position while the parts are heat treated at a temperature on which the transfer tape decomposes and its glass, glaze or ceramic content creates a solid bond between the ferrite parts.
- FIG. 3 An alternative construction method is shown in FIG. 3 where there are two back gaps" 10 instead of one.
- two back gaps 10 instead of one.
- on replay head it is desirable to keep the back gap as small as possible whereas on recording head a back gap different from zero is sometimes desirable in order to avoid saturation of the heat material.
- a magnetic recording/reproducing head comprising a prefmished core of a magnetic material having pole faces defining at least one gap wherein said pole faces are bonded to each other by a layer of electrically conductive material of metal powder intermixed with suitable flux.
Abstract
A magnetic transducer with a conductive gap spacer of metal powder intermixed with a suitable flux for bonding the pole faces together.
Description
United States Patent [151 3,641,281 Varadi et al. 1 Feb. 8, 1972 [54] MAGNETIC TRANSDUCER HAVING A CONDUCTIVE METAL POWDER GAP SPACER Inventors: Peter F. Varadi, 10500 Rockville Pike,
Rockville, Md. 20852; Laslo G. Sebestyen, 41 Ash Boume Road, Esling, London Division of Ser. No. 390,435, Aug. 18, 1964, Pat. No. 3,495,045.
U.S. Cl. ..179/l00.2 C, 340/174.1, 29/603 Int. Cl ..G1 lb 5/24, G1 1b 5/42 Field of Search ..l79/100.2 C; 340/l74.1 F;
[56] References Cited UNITED STATES PATENTS 2,771,969 1 1/1956 Brownlow ..29/603 2,786,897 3/1957 Schwarz 179/1002 3,188,400 6/1965 Vilensky... 179/1002 3,411,202 11/1968 Schwartz 179/1002 Primary Examiner-Bernard Konick Assistant Examiner-J Russell Goudeau Attorney-- [57] ABSTRACT A magnetic transducer with a conductive gap spacer of metal powder intermixed with a suitable flux for bonding the pole faces together.
l Claims, 3 Drawing Figures l 8 m 1 4 m 3 FIG! FIG.2
INV EN TORS PETE/7 E VARAD/ By L. 6480/? SEBE'STYEW MAGNETIC TRANSDUCER HAVING A CONDUC'IIVE METAL POWDER GAP SPACER This invention is a divisional of my copending application, Ser. No. 390,435, filed Aug. 18, 1964, now US. Pat. No. 3,495,045 entitled, Transducer Head for Magnetic Recording/Reproducing Apparatus.
The invention pertains to a transducer head for magnetic recording and reproducing apparatus and is particularly suitable for recording and reproducing very high frequency signals which occuramong others-in predetection recording of radar signals or recording and reproducing television programs on magnetizable medium.
The capability of the magnetic head of reproducing very high frequencies or, as they appear on the magnetizable medium, very short wavelengths is primarily determined by the nonmagnetic transducer gap in the head and the core material. For satisfactory reproduction of a recorded signal the transducer head in the reproducer head must be considerably less than the wavelength on the medium. A numerical example will illustrate the order of magnitudes. Let us assume that the recorded signal is 5 Mc./sec. and that the head-to-medium speed is 1,000 in./sec. Even at that high relative speed the recorded wavelength is 200 microinches long and it is desirable to keep the reproducer head gap to say 100 microinches. In the past shims of nonmagnetic materials such as phosphorbronze or aluminum have been positioned between the confronting end faces which are defining the boundaries of the physical gap. Whereas such foils are commercially produced, their assembly needs highly skilled labor and it appears that below 100 microinches thickness the production and application of foils runs into serious practical difficulties.
An alternative to the thin-foil method is the electroplating; this method is not considered suitable because of the edge effect, i.e., the thickening of the plating along the edges.
Another alternative is the vacuum-depositing of nonmagnetic materials such as gold, silicon or silicon monoxide. The difficulty in maintaining a controlled and uniform thickness by vacuum depositing is well known by those conversant with this art; however, up to now this has been the most successful way of producing thin gaps in spite of the expensive and complicated process.
The object of the invention is to provide a magnetic head with a very short and controlled nonmagnetic transducer gap.
A further object of the invention is to provide this gap by a method suitable for mass production.
Another object of the invention is to provide the gap in such a manner which disposes with the spring or retainer or casting which is necessary when applying any of the previously known methods.
The invention will be readily understood by way of an example, reference being made to the accompanying drawing in which FIG. 1 is the side view of a magnetic head.
In FIG. 1 the first pole piece 1 and the second pole piece 2 each are carefully lapped along AA and BB and are wound with coils 33 and 44. The core material may be any high permeability material such as Mu-metal, ferrite etc. The transducer gap 11 is formed by a layer of glass which forms an inseparable bond with the core material. Whereas in the past attempts have been made to use glass as gap spacer material, technological difficulties prevented it from becoming a practical proposition.
The gap, according to the invention, is formed by means of a heavily loaded plastic foil which is called transfer tape." This heavily loaded transferable tape can be prepared from glass, glazing or ceramic material to accurate thickness.
The transferable tape is prepared by laminating a slurry containing a suitably low particle size powder onto a carrier film. The thickness and density of this laminated layer can be accurately controlled prior to its application. The layer of the heavily loaded tape can then be transferred from its carrier to the pole faces of the magnetic transducer head to be coated,
either by heat or by using a suitable solvent or by utilizing an adhesive layer. The latter appears to be the method most suitable to mass production and will be described in detail.
A typical transferable tape, thus, consists of:
a. A thin, uniform carrier film of materials such as polyethylene, polyvinylchloride or Teflon;
b. A heavily loaded layer of glass, glazing, or ceramic powder in a binder such as nitrocellulose, polybutylmethacrylate or polyvinylalcohol and plasticizer. The ratio of these components can be varied according to the shape of the pole pieces from 98 percent solid powder and 2 percent plastic material to 36 percent solid powder and 64 percent plastic material.
c. And adhesive layer such as starch, synthetic rubber or polyvinylalcohol.
The preparation of the transferable tape is per se known and not claimed as an invention.
The application of transferable tape will be more readily understood on hand of FIGS. 2 and 3.
In FIG. 2 the carrier film 5 which can be e.g., polyethylene, polyvinylchloride or Teflon carries the heavily loaded layer 6 which is glass, glazing or ceramic powder uniformly distributed in a film-forming material such as nitrocellulose, polyacrylates or polyvinylacetate. A further layer 7 is an adhesive such as starch, synthetic rubber or polyvinylalcohol.
The transducer gap is prepared by bringing the ferrite head in contact with the transfer tape under small pressure. On removing the ferrite head from the transfer tape, the heavily loaded layer will adhere to the area of the ferrite head which was in contact with the tape. The transducer gap can now be completed by pressing according to the desired gap thickness a clean or a similarly treated part 9 against part 8 and holding them in position while the parts are heat treated at a temperature on which the transfer tape decomposes and its glass, glaze or ceramic content creates a solid bond between the ferrite parts.
An alternative construction method is shown in FIG. 3 where there are two back gaps" 10 instead of one. As well known to those skilled in the art of tape recording, on replay head it is desirable to keep the back gap as small as possible whereas on recording head a back gap different from zero is sometimes desirable in order to avoid saturation of the heat material.
The glass, glazing or ceramic material can be selected according to the composition of the ferrite or other highperrneability material which is normally used for magnetic record/reproducer heads. As an example, glass frits made by grinding lead glasses such as Coming 7570 glass and glass sorts sold under the trade name of Pyroceram by Corning Glass Works or soda-potash glasses were successfully utilized.
The transfer tape method can be used also for providing a very thin insulating layer on the ferrite or other magnetic head material underneath the coils.
Whereas in the description we referred to glass, glazing or ceramic" materials as the application of transfer tape method offers the greatest advantage at those, the method can be equally well applied to provide a nonmagnetic but electrical conductor gap such as gold, silver, platinum or copper, or the same materials intermixed with suitable flux.
Since many changes could be made in the specific combinations of materials disclosed herein and many apparently different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as being illustrative and not in a limiting sense.
What we claim is:
1. A magnetic recording/reproducing head comprising a prefmished core of a magnetic material having pole faces defining at least one gap wherein said pole faces are bonded to each other by a layer of electrically conductive material of metal powder intermixed with suitable flux.
Claims (1)
1. A magnetic recording/reproducing head comprising a prefinished core of a magnetic material having pole faces defining at least one gap wherein said pole faces are bonded to each other by a layer of electrically conductive material of metal powder intermixed with suitable flux.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US39043564A | 1964-08-18 | 1964-08-18 | |
US87029369A | 1969-11-28 | 1969-11-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3641281A true US3641281A (en) | 1972-02-08 |
Family
ID=27013134
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US870293A Expired - Lifetime US3641281A (en) | 1964-08-18 | 1969-11-28 | Magnetic transducer having a conductive metal powder gap spacer |
Country Status (1)
Country | Link |
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US (1) | US3641281A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2754536A1 (en) * | 1976-12-07 | 1978-06-08 | Victor Company Of Japan | FERRITE CORE MAGNETIC HEAD WITH REINFORCEMENT FILLER |
US4139408A (en) * | 1977-09-28 | 1979-02-13 | Illinois Tool Works Inc. | Adhesive fastener article |
US4163885A (en) * | 1977-09-28 | 1979-08-07 | Illinois Tool Works Inc. | Induction heating core and heating system for adhesive fasteners |
US4163884A (en) * | 1977-09-28 | 1979-08-07 | Illinois Tool Works Inc. | Induction heating core for adhesive fastening systems |
US4180835A (en) * | 1977-06-09 | 1979-12-25 | Sony Corporation | Magnetic erasing head with gaps utilizing high flux density and high permeability |
US6018862A (en) * | 1997-10-07 | 2000-02-01 | Seagate Technology, Inc. | Thin-film magnetic recording head using a plated metal gap layer |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2771969A (en) * | 1952-11-26 | 1956-11-27 | Gulton Ind Inc | Method for joining metallic and ceramic members |
US2786897A (en) * | 1951-04-19 | 1957-03-26 | Siemens Ag | Magnetic recorder |
US3188400A (en) * | 1961-01-09 | 1965-06-08 | Ampex | Ferrite coating |
US3411202A (en) * | 1964-06-25 | 1968-11-19 | Ibm | Method of manufacturing recording heads |
-
1969
- 1969-11-28 US US870293A patent/US3641281A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2786897A (en) * | 1951-04-19 | 1957-03-26 | Siemens Ag | Magnetic recorder |
US2771969A (en) * | 1952-11-26 | 1956-11-27 | Gulton Ind Inc | Method for joining metallic and ceramic members |
US3188400A (en) * | 1961-01-09 | 1965-06-08 | Ampex | Ferrite coating |
US3411202A (en) * | 1964-06-25 | 1968-11-19 | Ibm | Method of manufacturing recording heads |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2754536A1 (en) * | 1976-12-07 | 1978-06-08 | Victor Company Of Japan | FERRITE CORE MAGNETIC HEAD WITH REINFORCEMENT FILLER |
US4180835A (en) * | 1977-06-09 | 1979-12-25 | Sony Corporation | Magnetic erasing head with gaps utilizing high flux density and high permeability |
US4139408A (en) * | 1977-09-28 | 1979-02-13 | Illinois Tool Works Inc. | Adhesive fastener article |
FR2404760A1 (en) * | 1977-09-28 | 1979-04-27 | Illinois Tool Works | FIXING DEVICE MAINTAINED BY GLUE |
US4163885A (en) * | 1977-09-28 | 1979-08-07 | Illinois Tool Works Inc. | Induction heating core and heating system for adhesive fasteners |
US4163884A (en) * | 1977-09-28 | 1979-08-07 | Illinois Tool Works Inc. | Induction heating core for adhesive fastening systems |
US6018862A (en) * | 1997-10-07 | 2000-02-01 | Seagate Technology, Inc. | Thin-film magnetic recording head using a plated metal gap layer |
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